Light projector



ZIESIII I-B 8?? L. BELL.

LIGHT PROJECTOR.

APPLICATION FILED MAY I. I9I9. RENEWED MAR. 24. 192i.

1 ,43 5 ,372, Patented Nov. 14, 1922;

jzzvenior Z0 zzz's'fieli I I? Aarizuz i To all it may concern: i

tors, of which the following is aspecifica- Patented Nov. 14, 1922.

UNITED STATES.

LQUIS' BELL, or NEWTON, MASSACHUSETTS, mien-s 'ro nnwaan' N. Gama, TRUSTEE, or unwrou, uassacnusarrs, 1

' LIGHT 1 noaiitrro a* Application filed K947151919, Serial No. 294,018. s e-ma 24, 1921; 8er1al no. 455,338.-

Be it'lmown that I, Louis BELL, a citizen and useful Improvements in Light Projec tion.

The subject'matter of my present 'inven' tion has to do with light projectors of combined reflective and refractive function. In

my previous application Serial No. 277,957,

5 filed February 19, 1919, I discussed the nature of these 115..

problems at some length and disclosed certaln principles involved in that invention with embodiments thereof.

, My present invention involves still further improvements of great practical advantage. In my present invention I utilize a symmetrical surface of rotation preferably spherical, as a rear-or reflecting surface, combining it with a surface of refraction which may generally be defined as a surface having radii of curvature dilfering from the homologous coacting radii of the rear surface. By this combination I am able to pro- 7 shown simple forms of my invention illustrating the principles involved, but slightly exaggerated for the purposes of illustration.

I Fig. 3 a similar Throughout the specification and drawings like reference numerals are employed to in dicate corresponding parts, and in the draw:

in s:

Fig. 2 a transverse sectional view thereof;

fied form.

same, and

Figs. 5 and 6 similar views of In the form shown in Fig. 1 the reflector is provided. with a spherical curvature of, the back ab, this curvature being obvious- V g tlon, the back being 7 of the United States, residingat' Newton, A county of Middlesex, Commonwealth of v Massachusetts, have invented certain'new? ticalsection'shows a 111 a transverse section acurve e -f, the curv ter which lies'about the center of the curve illustrative -Figs. 5 and 6 the to. be confused with vertical section of a modief tstfront is within the-limitsjof my inven- Fig. 4 a transverse sectional view of the." v I 2 What I therefore claim secure by "Letters Patent is 1y 'thesame in vertical and transverse secis struck' from a cenab. The curves. ef anda1b are struck from centers in the same axis but with radii. of dlfi'erent length. I

In the form shown in Figs. 3 and 4, the rear. face isformed with a curvature g--h which for the purpose of illustrating a mod lficat on, may be considered as parabolic. Th s s combined with a front surface which in vertical section shows a curvature "Ii-j andin lateral section, as shown in 'lligL i,

'a curvature k-Z. fiThe, sections as shown in F1g.3 show coax al curves on' front and back; but of different radii. The front curve 23-7 is of shorter radius. In -the sec tion shown in Fig. 4 the bounding curves are also coaxial but with the front curve 70-4 of longer radius.

surface of vertical decentering for it's vertical sweep m-m. and of lateral decentering for its lateral sweep 0-p. By using such unsymmetrical refracting surfaces I am able to secure distribution from a symmetrical reflecting surface. This refractive distribution is not the symmetrically, corrective function of therefraction in the angln mirror, but

predetermined una predetermined unsymmetrical I provides on the con-j. trary a comblnation .for

ace in the form shov n In the form-shown in front face is a toroidal.

symmetrical refractive distribution jin. the

projected beam; These mi orsare provided an .incandescent bulb tion.

andfdesire to with aperture E through which a sourceof light such .as

e. ,..;-ject ed.-, ig. 1 shows avertical section of a reflector illustrating one form of my inventiom;

S pr i a; threats as a ;-ing surface is combined with an unsymmet r cal refracting curvature .or curvatures, of

1. A light projector of. transparent ma surface of symmetrical curvature and a re- "terial havinga 'specularly reflecting rear 1 V origin.

2. A light projector 'of transparent material havin a specularly reflectmg rear surface of sp erical curvature and a refracting front surface of toroidal form.

3; A light pro'ector of transparent material having a re ecting rear surface of rev-' olution and a front refracting surface having radii'of curvature differing in different. meridians at the same radial distance fromthe axis of the rear surface.

4. A light projector of transparent material having ;a specularly reflecting curved rear surface of constant radius of-curvature,

and a front refracting surface having plural radii of curvature differing from the radius of the rear surface in length and 'plane of 5. A rial having a specularly reflecting spherical rear surface and a front refracting surface having plural radii of curvature v rear surface.

light projector of transparent. mate- 6. In a light projector, a concave glass mirror having a silvered rear constituting asurface of revolution, a source of light substantially in the corresponding axis of revolutlon, and a non-coaxial front surface refractively diverting light rays from'said source from a a distribution symmetrical about the axis of said silvered rear surface. 7; As a new articleof manufacture, a llght projecting mirror having a spherical mechanically polished and silvered rear surface centrally'perforated, and arefracting front surface molded into-a form of variant curvature axially unsymmetrical with the .In testimony whereof I afiix my signa- 'ture in presence of two witnesses. 

